rows = [
{'address': '5412 N CLARK', 'date': '07/01/2012'},
{'address': '5148 N CLARK', 'date': '07/04/2012'},
{'address': '5800 E 58TH', 'date': '07/02/2012'},
{'address': '2122 N CLARK', 'date': '07/03/2012'},
{'address': '5645 N RAVENSWOOD', 'date': '07/02/2012'},
{'address': '1060 W ADDISON', 'date': '07/02/2012'},
{'address': '4801 N BROADWAY', 'date': '07/01/2012'},
{'address': '1039 W GRANVILLE', 'date': '07/04/2012'},
]

from operator import itemgetter
from itertools import groupby


#groupby连续的值须先排序
rows.sort(key=itemgetter('date'))
for date, items in groupby(rows, itemgetter('date')):
    print(date)
    for item in items:
        print(' ', item)

from collections import defaultdict
rows_by_date = defaultdict(list)

for row in rows:
    rows_by_date[row['date']].append(row)

for key, value in rows_by_date.items():
    print(key)
    for item in value:
        print(' ', item)
